Experimental Study of Premixed-Charge Compression Ignition Mode in Low Load Fueled With Butanol Isomers and Diesel Binary Fuels in a Common-Rail Diesel Engine

Abstract

Low NOx and particulate matter (PM) emissions are simultaneously attempted to implement via an experimental study on diesel/butanol isomers binary fuels in premixed-charge compression ignition (PCCI) mode. N-butanol, iso-butanol, sec-butanol, and tert-butanol were blended with diesel in a certain volume ratio of 0.24:0.76, denoted as N24, I24, S24, and T24, respectively. The indicated thermal efficiency (ITE) of binary fuels in PCCI mode decreases slightly than that in direction injection (DI) mode. T24 obtains higher ITE than the other three test fuels with 50% exhaust gas recirculation (EGR). NOx formation is certainly inhibited more than 60% in PCCI mode, especially when the EGR rate is 50%. PCCI mode produces more CO, HC, and carbonyl emissions than DI mode to varying degrees; under these circumstances, T24 tends to have the lowest emissions among four test fuels, reflecting the potential of tert-butanol as a diesel alternative fuel. Butanol isomers have a vital contribution on particulate matter emissions inhibition for both PM total number and total mass. Tert-butanol tends to form accumulation mode particle, and n-butanol tends to form nucleation mode mainly caused by molecular structure diversity of isomers. The geometric mean diameter of diesel/butanol isomers increases in PCCI mode compared with that in DI mode.